Solar regeneration of powdered activated carbon impregnated with visible-light responsive photocatalyst: Factors affecting performances and predictive model

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• 作者：Pow-Seng Yap ; Teik-Thye Lim ; ^{cttlim@ntu.edu.sg}
• 关键词：Regeneration ; Micropollutants ; Solar photocatalysis ; Spent activated carbon ; Titanium dioxide ; Water reclamation
• 刊名：Water Research
• 出版年：2012
• 期刊代码：57_00431354
• 类别：civ
• 出版时间：1 June, 2012
• 卷：46
• 期：9
• 页码：3054-3064
• 文件大小：1269 K

摘要

This study demonstrated a green technique to regenerate spent powdered activated carbon (AC) using solar photocatalysis. The AC was impregnated with a photocatalyst photoexcitable under visible-light irradiation to yield a solar regenerable composite, namely nitrogen-doped titanium dioxide (N-TiO₂/AC). This composite exhibited bifunctional adsorptive-photocatalytic characteristics. Contaminants of emerging environmental concern, i.e. bisphenol-A (BPA), sulfamethazine (SMZ) and clofibric acid (CFA) which exhibited varying affinities for AC were chosen as target pollutants. The adsorption of BPA and SMZ by the N-TiO₂/AC was significantly higher than that of CFA. The performance of solar photocatalytic regeneration (SPR) of the spent N-TiO₂/AC composite generally increased with light intensity, N-TiO₂ loading and temperature. The regeneration efficiency (RE) for CFA-loaded spent composite was the highest compared to the other pollutant-loaded spent composites, achieving 77%within 8 h of solar irradiation (765 W m^鈭?). The rate-limiting process was pollutant desorption from the interior AC sorption sites. A kinetic model was developed to predict the transient concentration of the sorbate remaining in the spent composite during SPR. Comparison studies using solvent extraction technique indicated a different order of RE for the three pollutants, attributable to their varying solubilities in the aqueous and organic solvents.